6: Dave Carroll

United baggage handlers David Zalubowski/AP Images United Airlines baggage handlers getting to work at Denver International.

When the Canadian folk-pop group Sons of Maxwell began their tour of Nebraska in 2008, they were disheartened to find from their seats in the rear of the United Airlines flight that baggage handlers were heavily tossing their guitars onto the plane. Upon landing and traveling to a hotel in Omaha, the band found that while the bass was intact, a $3,500 Taylor guitar had been broken.

The guitar's owner, guitarist Dave Carroll, began what would be a long plight toward reimbursement for his instrument. After nine months of calling customer service and following their suggestions in filing a claim, as well as spending $1,200 to repair the guitar, Carroll's claim was finally denied by United, based on several points, including that he hadn't shown the guitar to officials in Omaha [source: Carroll].

So Carroll decided that he would exact revenge by recording a series of songs, which came to be called the "United Breaks Guitars" trilogy. He uploaded them onto YouTube, where they went viral and racked up more than 4 million views in less than a month. Carroll's revenge on United may have had an impact on the company's bottom line: Within four days of the first video's launch, United's stock dropped in value by $180 million, or 10 percent of its market cap [source: Ayres].